Micro-Abrasive Blasting Device for Dental Applications and Methods

ABSTRACT

A micro-abrasive blasting device comprises a mixing chamber, a delivery conduit extending from external the mixing chamber to the mixing chamber and a discharge conduit extending from the mixing chamber. Abrasive material may selectively be sealed in the chamber by positioning the discharge conduit to abut the inlet port. The chamber may be spherical to deliver consistent powder perturbation at all mixing chamber orientations. Methods of using the device are disclosed. Methods of making the device by blow molding are disclosed.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a division of U.S. application Ser. No. 12/551,416 filed Aug.31, 2009, which is a division of U.S. application Ser. No. 11/452,067filed Jun. 13, 2006, all by Groman.

FIELD

The invention relates generally to the field of devices for propellingabrasive powder with intent to etch the surface of a target material.More specifically, the present invention relates to a micro-abrasiveblasting device powered by a pressurized-gas source for use with dentalprocedures.

BACKGROUND

Abrasive blasting devices operate on the physical property that gas at ahigher pressure flows towards and into gas at lower pressure. Whenabrasive powder is mixed with gas at higher pressure, the gas carriesthe abrasive powder as the gas accelerates and flows to the lowerpressure. As the gas and abrasive powder blast the target material athigh speed, the impact of the particles removes layers of the targetmaterial.

In dentistry this technology is known as micro-abrasion and is used toachieve a variety of goals—such as to remove foreign material or to dulla shiny surface, roughen or etch the surface to enhance bonding qualityand to remove decay by drilling and cutting tooth structure.

Air abrasion devices date back decades with patented inventions bypioneers such as Ziegler U.S. Pat. No. 2,612,732, Crow U.S. Pat. No.2,725,684, Schachter U.S. Pat. No. 3,626,841 and Paache U.S. Pat. No.2,441,441.

Over the years two main approaches to air abrasion devices developedwith Ziegler and Schechter following one approach and Crowe and Passchefollowing another. One approach has been to provide a stationary mixingapparatus for generating the abrasive laden air stream and deliveringthe abrasive laden air stream through an extended hand-piece fordirecting the stream onto the target surface. Another approach has beento integrate the mixing apparatus into the hand-held device.

The first approach facilitates more complex mechanisms and manyoperational options since the size and weight of the device are of noconcern. Because the extended hand-piece delivers the abrasive laden airstream independent of the mixing operation, the hand-piece can be heldat any orientation during operation. Deardon et al. U.S. Pat. No.6,083,001 discloses a dental air abrasion system in which the flow ofthe particles is electronically controlled by pressure differentials.Rainey U.S. Pat. No. 6,093,021 discloses an automated control systemwhich utilizes a gas stream mounted particulate sensor to regulate fluidflow rates into and around the ultrasonically agitated mixing chamber inorder to accurately maintain the abrasive concentration in the airstream. Various methods for reducing the overspray of the abrasive havealso been developed for these devices. Ho U.S. Pat. No. 5,356,292,Coston U.S. Pat. No. 5,197,876, and Burns et al. U.S. Pat. No. 6,024,566disclose add-on splatter guard and collector attachments to air abrasiondevices.

In the second approach, the size, weight, and ergonomic shape of thedevice are significant factors. Herald et al. U.S. Pat. No. 5,199,299and Burns et al. U.S. Pat. No. 6,439,966 disclose innovativehand-holdable air abrasion devices which mount the mixing apparatus intothe hand-piece. The drawback of this approach is that the operation ofthese devices is limited by the orientation of the mixing chamber.

An adjunct to the second approach has been the concept of simpleself-contained air abrasion devices—such as Hertz U.S. Pat. No.5,839,946 (and its derivative patents U.S. Pat. No. 6,287,180, U.S. Pat.No. 6,951,505, and Granted application Ser. No. 09/939,865), Groman U.S.Pat. No. 6,398,628 (and its derivative patents U.S. Pat. No. 6,347,984and Pending application Ser. No. 10/144,228), Schur et al. U.S. Pat. No.6,004,191, and Trafton et al. U.S. Pat. No. 6,354,924. These devicesrely on the air stream to perturb the abrasive and generate the mixingaction based on Stark et al. U.S. Pat. No. 4,475,370 fixed air abrasiondevice for treating dental castings.

Merging of Stark's blow-through mixing method into the hand-piece so themixing chamber is held between the user's fingers has taken air abrasionart to a new level. Because of their simplified structures, simpleself-contained air abrasion devices tend to be less expensive tomanufacture and can therefore be marketed to the user as disposableinstruments.

With increased emphasis in Medical, Pharmaceutical, Cosmetic and Dentalapplications on reduced cross-patient contamination, there has been asignificant drive towards single usage disposable packaging and devices.With advances in materials and fabrication technologies the cost ofthese devices has been significantly reduced. Dougherty U.S. Pat. No.4,391,590 discloses a syringe and stopper like cartridge device fordispensing material while Hertz U.S. Pat. No. 5,839,946 patent disclosesthe formulation an air abrasion instrument from a syringe and stoppertype structure. Both innovations capitalize on the lower cost offabrication and the well established production methods of a syringe andstopper configuration.

Simple self-contained prior art air abrasion devices support anelongated cylindrical chamber with an inlet conduit for delivering theair into the mixing chamber and a discharge conduit for carrying theair-abrasive mixture out of the mixing chamber. The mixing chambers areutilized as a reservoir for storing the abrasive powder. Once thereservoir is depleted of abrasive material, the devices are discardedand therefore function as disposable instruments which do not requiresterilization post intra-oral use.

To prevent the abrasive material from escaping the mixing chamber orbecoming contaminated prior to use, simple self-contained prior art airabrasion devices add additional components which seal the inlet andoutlet ports and conduits. While the Hertz U.S. Pat. No. 5,839,946, andSchur et al. U.S. Pat. No. 6,004,191 devices include passive caps whichmust be removed prior to using the instrument, Hertz U.S. Pat. No.6,951,505 and U.S. Pat. No. 6,287,180, and Groman U.S. Pat. No.6,398,628 and U.S. Pat. No. 6,347,984 add functional components whichactively prevent the abrasive from exiting the mixing chamber. GromanU.S. Pat. No. 6,398,628 has a filter that prevents the abrasive fromexiting the device's inlet port and a movable discharge conduit whichprevents abrasive material from exiting the mixing chamber when thedischarge conduit inlet port abuts the side wall of the mixing chamber.Groman pending application Ser. No. 10/144,228 support a deformablegasket at the discharge port internal to the mixing chamber which openswhen flow is present. Hertz U.S. Pat. No. 6,951,505 has a deformableseal at the inlet port external to the mixing chamber which functions asa check-valve that allows the pressurized-gas to enter the instrumentbut prevents abrasive from exiting the instrument. Groman U.S. Pat. No.6,398,628 discloses a deformable and movable cap configurations whichblock both the delivery conduit inlet and discharge conduit outlet priorto use.

Another disposable delivery method disclosed by Zhang et al. U.S. Pat.No. 6,343,717 attempts to address the containment of stored materialutilizing a pipette structure. A typical pipette consists of a slenderpipe or tube that is used to transfer or measure small quantities ofmaterial from one location to another. The most common type of pipetteconsists of a small tube that widens into a bulb at the middle.

Zhang et al. pipette structure is made of a rigid or resilient materialthat is pre-filled with a pharmaceutical or cosmetic product and is usedonce and then discarded. Zhang et al. discloses a plurality of ways bywhich the disposable pipette can be sealed to contain the material andthen unsealed by the user prior to use for dispensing the storedmaterial. According to Zhang's et al. invention the majority of materialis retained within the bulb section of the pipette, but Zhang's et al.sealing methods permit the contained material to migrate into the topand bottom tube sections. Although Zhang's et al. use of a pipettestructure leads to a very cost effective means of delivering thecontained material, Zhang's et al. sealing methods are not compatiblewith the needs of air abrasion devices.

Pressurized air stream is delivered to the simple self-contained airabrasion devices of Hertz, Groman, Schur, and Trafton via customconnectors which engage the device externally and to form a seal withthe device body to deliver the pressurized air to the mixing chamberdelivery port. The connectors are designed to supply clean dry air inorder to maintain the abrasive powder dry, since any moisture causesclumping of the abrasive material and therefore the malfunction of thedevice. The dry air is required because the gas delivery conduit leadsdirectly into the mixing chamber; therefore any liquid present at theentry to the device gets trapped in the mixing chamber. Hertz et al.U.S. Pat. No. 6,293,856 discloses a connector with additional conduitsfor carrying other types of fluids passively through the mixing chamber.This configuration requires a very complex connector to assure theseparation of the fluids delivered to the air abrasion instrumentwithout contaminating the mixing chamber. Custom connectors which supplydry air add to the installation cost and complexity of these disposabledevices. And because they attach to the body of the devices, theseconnectors are typically very bulky.

Referring to FIG. 1, prior art self-contained air abrasion devices use ablow-through methodology to agitate the abrasive powder. Morespecifically, these devices utilize the delivery conduit to deliver thegas stream into the abrasive material. As the gas stream blows throughthe abrasive material, the abrasive material is agitated. Gravity isutilized to assure that the non-aerated abrasive remains at the bottomof the mixing chamber. As the air stream reverses direction towards thedischarge conduit inlet, aerated particles are captured by the airstream. The abrasive laden air stream is pushed out of the mixingchamber through the discharge conduit by the higher pressure gas source.

In their reduction to practice, both the Schur and Groman devicesrequire the user to maintain the orientation of the device so the mixingchamber points downward. The attached user instructions for the Schurand Groman devices outline the specific user instructions cautioning theuser about mis-orienting the mixing chamber. To compensate for hisshortcoming, the marketed Groman instrument provides a finger bendabledischarge conduit. The marketed Schur device provides a bending tool, sothe user is able to form the delivery conduit to reach upper surfaceswhile maintaining the proper orientation of the mixing chamber.

Referring to FIG. 2, if the user attempts to utilize these prior artdevices with the mixing chamber horizontal or upside down, the abrasivematerial is pushed directly into the discharge conduit without beingproperly mixed with the air steam. This leads to a concentration ofabrasive material to exit the device in an uncontrolled manner, whichcreates a cloud of abrasive dust or clogs up the discharge conduit asthe abrasive powder binds. Additionally, in certain orientations thedelivery conduit is not immersed in the abrasive material which alsodisrupts the mixing operation of these prior art devices. In fact, thepressurized-gas exiting the delivery conduit creates a back pressure onthe abrasive within the mixing chamber causing the abrasive powderparticles to bind together instead of mix with the air stream. Mostimportantly, these disruption in flow can lead to a defective clinicalprocedure which either under or over etches the target tooth surface.

SUMMARY

The invention disclosed herein addresses the following shortcomings withthe prior art simple self-contained air abrasion devices:

1) Eliminates the need for the inlet and outlet caps or other sealingmethods.

2) Makes the device insensitive to liquids at the pressurized-gasconnection.

3) Makes the air abrasive mixing operation independent of theorientation of the mixing chamber.

4) Eliminates back pressure buildup within the mixing chamber.

5) Eliminates the need for a bulky custom connection to the instrumentfor pressurized-gas delivery.

In addition, this invention teaches a new innovative method forconstructing the air abrasion device out of a continuous tubing formedinto a disposable pipette structure.

Accordingly, several objects and advantages of the present invention(s)may include to:

1) Reduce component count by utilizing the discharge conduit inconjunction with the delivery conduit inlet to seal the abrasivematerial within the mixing chamber.

2) Create a bypass to the mixing chamber so liquids in thepressurized-gas connection are purged out of the system withoutcontaminating the abrasive within the mixing chamber.

3) Provide a spherical mixing chamber which assures a distal separationbetween the discharge conduit inlet and the abrasive powder at allmixing chamber orientations.

4) Eliminate the air stream reversal within the mixing chamber so backpressure is never created on the abrasive powder.

5) Extend the delivery conduit external to the mixing chamber so aslender handheld gas supply connector and standard tube fittings can beutilized for pressurized-gas delivery.

6) Make the disposable pipette structure usable for air abrasionapplications in order to further reduce the manufacturing costs.

Still another object of the invention is that the material in the bulbof the pre-filled pipette is protected from contamination or spillage bythe discharge conduit.

A micro-abrasive blasting device constructed from a disposable pipettestructure comprising a delivery conduit extending from a deliveryconduit inlet through a tapered section to form a delivery conduitoutlet and a inlet port; contiguous pipette structure expands from inletport to form a hollow bulb mixing chamber and then narrows to form adischarge port section; a discharge conduit is in fluid communicationswith discharge port and extends from a discharge conduit inlet internalto mixing chamber to a discharge conduit outlet external to mixingchamber; a particulate matter is disposed within mixing chamber wall;discharge conduit inlet abuts inlet port preventing particulate matterfrom exiting mixing chamber. A separation gap between the deliveryconduit outlet and discharge conduit inlet is created as dischargeconduit is displaced so discharge conduit inlet no longer abuts inletport; As pressurized-gas is supplied to micro-abrasive blasting devicethrough the delivery conduit inlet, the pressurized-gas flows throughthe delivery conduit and out of the inlet port, into mixing chamber. Asflow is initiated, particulate matter instantaneously mixes with thegas-steam within hollow resilient bulb mixing chamber and the powder-gasmixture flows through discharge conduit to strike target surface.

BRIEF DESCRIPTION OF THE DRAWINGS

Various other objects, advantages, and features of the invention willbecome apparent to those skilled in the art from the followingdiscussion taken in conjunction with the following drawings, whereclosely related figures have the same number but different alphabeticsuffixes:

FIGS. 1 (1A, 1B) and 2 are views of prior art micro-abrasive blastingdevices.

FIGS. 3 (3A, 3B, 3C) are cross-sectional views of the innovativemicro-abrasive blasting device and isometric view of the innovativedevice mounted into a handpiece connector. FIG. 3D is a perspectiveview.

FIGS. 4 (4A, 4B) are cross-sectional views of the innovativemicro-abrasive blasting device fabricated out of a pipette structure.

FIGS. 5 (5A, 5B) and 6 (6A, 6B, 6C) are isometric and cross-sectionalviews of micro-abrasive blasting devices with spherical mixing chamber.FIG. 5C is a perspective view.

FIGS. 7 (7A, 7B) are cross-sectional views of an embodiment of themicro-abrasive blasting device with discharge conduit bearing integralto the pipette structure.

FIGS. 8 and 9 are cross-sectional views of an embodiment of themicro-abrasive blasting device with an integrated protective nozzleguard and integrated particle deflector integral to the pipettestructure.

REFERENCE NUMERALS IN DRAWINGS

10 discharge conduit

12 discharge conduit inlet

14 discharge conduit outlet

23 mixing chamber

25 mixing chamber wall

27 inlet port

29 discharge port

30 delivery conduit

32 delivery conduit external section

33 delivery conduit tapered section

34 delivery conduit internal section

35 delivery conduit inlet

37 delivery conduit outlet

40 target surface

45 separation gap

48 pressure gradient

50 particulate matter

55 handheld supply connector

75 micro-abrasive blasting device

80 pipette structure

82 discharge conduit bearing

83 Discharge conduit stop

85 protective nozzle guard

87 nozzle guard separation point

90 particle deflector

93 particle deflector separation point

95 capped position end

97 mixing position end

DETAILED DESCRIPTION

It is to be understood that the disclosed embodiments are merelyexemplary of the invention, which may be embodied in various forms.Therefore, specific structural and functional details disclosed hereinare not to be interpreted as limiting, but merely as a basis for theclaims and as a representative basis for teaching one skilled in the artto variously employ the present invention in virtually any appropriatelydetailed structure.

Reference is now made to the drawings, wherein like characteristics andfeatures of the present invention shown in the various FIGURES (FIGs.)are designated by the same reference numerals.

First Embodiment

Referring to FIG. 3, a micro-abrasive blasting device 75 is disclosed;Micro-abrasive blasting device 75 comprises a mixing chamber 23 formedby a mixing chamber wall 25 and supports a inlet port 27 and a dischargeport 29; a delivery conduit 30 extending from a delivery conduit inlet35 external to mixing chamber 23 to a delivery conduit outlet 37internal to mixing chamber 23, by means of protruding into mixingchamber 23 through mixing chamber wall 25 at inlet port 27; a dischargeconduit 10 is in fluid communications with mixing chamber 23 atdischarge port 29, and extending from a discharge conduit inlet 12internal to mixing chamber 23 to a discharge conduit outlet 14 externalto mixing chamber 23; a particulate matter 50 is disposed within mixingchamber 23.

Delivery conduit 30 comprises a delivery conduit external section 32external to mixing chamber 23 and a delivery conduit internal section 34internal to mixing chamber 23 and a connecting delivery conduit taperedsection 33; external section 32 of delivery conduit 30 is preferablystraight and preferably supports an outer and inner diameter that fitsinto standard tube and hose connectors such as push-in or push-onconnector types; internal section 34 of delivery conduit 30 preferablysupports an inner diameter that is equivalent to the outer diameter ofdischarge conduit inlet 12.

Referring to FIG. 3D, extending delivery conduit 30 external to themixing chamber 23 facilitates a connection to a handheld pressurized-gassupply connector 55. Not only does this innovative configurationsimplify the type of connection required for supplying thepressurized-gas and therefore the cost of the air supply adaptor, italso facilitates a more narrow connection to the air abrasion device.Whereas, prior art devices connect to the mixing chamber body, thisembodiment connects to a narrower delivery conduit. Therefore, theinnovative micro-abrasive blasting device 75 may be mounted as adisposable tip onto a non-disposable handheld supply connector 55. Whilehandheld supply connector 55 is held by the user's fingertips, deliveryconduit 30 of micro-abrasive blasting device 75 mounts into handheldsupply connector 55 downstream of the user's fingertips. Because theinnovative micro-abrasive blasting device 75 does not support the user'sgrip and bulky supply connector, micro-abrasive blasting device 75 canbe made shorter and of less rigid material. This configuration greatlydecreases the complexity and cost of the micro-abrasive blasting device75.

Referring to FIG. 3A, discharge conduit inlet 12 abuts delivery conduitoutlet 37 as to prevent particulate matter 50 from exiting mixingchamber 23, thereby sealing particulate matter 50 within mixing chamber23. As delivery conduit external section 32 engages with apressurized-gas source, pressurized-gas is delivered to delivery conduit30 at delivery conduit inlet 35; the pressurized-gas passes throughdelivery conduit 30 into discharge conduit 10 to exit micro-abrasiveblasting device 75 at discharge conduit outlet 14. Since dischargeconduit inlet 12 abuts delivery conduit outlet 37 the pressurized gascan not enter mixing chamber 23. Therefore, any moisture or liquidresidue contained in or carried by the pressurized-gas does not entermixing chamber 23 and is discharged through micro-abrasive blastingdevice 75.

Referring to FIG. 3B, a separation gap 45 between the delivery conduitoutlet 37 and discharge conduit inlet 12 is created as discharge conduit10 is displaced so discharge conduit inlet 12 no longer abuts deliveryconduit outlet 37; As pressurized-gas is supplied to micro-abrasiveblasting device 75 through delivery conduit inlet 35, thepressurized-gas flows through delivery conduit 30 and out of deliveryconduit outlet 37 into mixing chamber 23. When gas flow is present,particulate matter 50 instantaneously mixes with the flowing gas and isdispensed through discharge conduit 10 to strike target surface 40. Oncemixing chamber 23 is depleted of particulate matter 50, micro-abrasiveblasting device 75 is removed from the pressurized-gas source anddiscarded.

Second Embodiment

Referring to FIG. 4, a micro-abrasive blasting device 75 is comprised ofa hollow resilient round tubular pipette structure 80 constructed of athermoplastic material such as polycarbonate, polyethylene, polyester,polystyrene, polypropylene, polysulfone, polyurethane,ethylene-vinyl-acetate or the like. The material may be transparent,translucent, opaque, or pigmented to indicate the type of abrasivepowder contained within the sealed mixing chamber. Pipette structure 80preferably has a circular cross section but can also be fabricated outof other cross sectional shapes.

Micro-abrasive blasting device 75 is comprised of a pipette structure 80which consists of three sections, a hollow bulb section forming a mixingchamber 23; a open ended hollow tubular delivery conduit 30 sectionsmaller in diameter and contiguous with the bulb section at inlet port27, for delivery of pressurized-gas; a hollow tubular discharge port 29section smaller in diameter and contiguous with the bulb section, fordischarging abrasive laden gas stream; a discharge conduit 10 in fluidcommunications with discharge port 29, and extending from a dischargeconduit inlet 12 internal to mixing chamber 23 to a discharge conduitoutlet 14 external to mixing chamber 23; a particulate matter 50 isdisposed within mixing chamber 23. Preferably, delivery conduit 30section extends from a delivery conduit inlet 35 through a externalsection 32 and a tapered section 33 to form a delivery conduit outlet 37and a inlet port 27.

The outer and/or inner diameter of delivery conduit external section 32is preferably selected to fit standard tube or hose fittings, while theinner diameters of inlet port 27 and discharge port 29 preferablysupport an inner diameter that is equivalent to or less than the outerdiameter of discharge conduit 10. Design selections of these diametersmay eliminate or reverse the gradient of delivery conduit taperedsection 33, rendering delivery conduit 30 a straight tube. The diameterof hollow resilient bulb mixing chamber 23 is preferably selected tosupport the appropriate quantity of particulate matter 50 to at leastperform one dental procedure.

Pipette structure 80 may be formed via blow-molding and/or tube swagingtechniques, or other thermo-forming processes. These methods wouldtypically require that one of the ends of the tubular pipette structure80 be sealed in order to entrap pressurized-gas for forming thecomponent during the blow-molding process. The sealed end may be formedat the delivery conduit inlet 35 of delivery conduit 30 section or atthe tip of discharge port 29 section. The sealed end may be trimmed offduring the assembly process of micro-abrasive blasting device 75 or justpunctured or cut to permit air flow into micro-abrasive blasting device75 when mounted onto a pressurized-gas connector. Additionally, thepressurized-gas connector could support cutting or puncturing means forbreaking the blow-molded seal when delivery conduit 30 is mounted on thepressurized-gas connector.

Referring to FIG. 4A, discharge conduit inlet 12 fits within or abutsinlet port 27 preventing particulate matter 50 from exiting mixingchamber 23. As delivery conduit external section 32 engages with apressurized-gas source, pressurized-gas is delivered to delivery conduit30 at delivery conduit inlet 35; the pressurized-gas passes throughdelivery conduit 30 into discharge conduit 10 to exit micro-abrasiveblasting device 75 at discharge conduit outlet 14. Since dischargeconduit inlet 12 abuts inlet port 27 the pressurized gas can not entermixing chamber 23.

Referring to FIG. 4B, a separation gap 45 between the inlet port 27 anddischarge conduit inlet 12 is created as discharge conduit 10 isdisplaced so discharge conduit inlet 12 no longer abuts inlet port 27;As pressurized-gas is supplied to micro-abrasive blasting device 75through delivery conduit inlet 35, the pressurized-gas flows throughdelivery conduit 30 and out of inlet port 27, into mixing chamber 23. Asflow is initiated, particulate matter 50 instantaneously mixes with thegas-steam within hollow resilient bulb mixing chamber 23 and thepowder-gas mixture flows through discharge conduit 10 to strike targetsurface 40.

Third Embodiment

Referring to FIG. 5, this preferred micro-abrasive blasting device 75 isalso constructed of a contiguous pipette structure 80 and operates asthe preferred embodiments of FIGS. 3 and 4. However, pipette structure80 of the FIG. 5 embodiment supports a mixing chamber wall 25constructed to form a hollow spherical bulb mixing chamber 23. Thespherical shape of mixing chamber 23 assures a distal separation betweenthe discharge conduit inlet 12 and the particulate matter 50 at allorientations of mixing chamber 23.

Referring to FIG. 6A, when micro-abrasive blasting device 75 is operatedin a horizontal orientation, particulate matter 50 is pulled by gravityto the mixing chamber wall 25 at the bottom surface of mixing chamber23. Therefore, during operation, the spherical configuration of mixingchamber 23 keeps particulate matter 50 distant from discharge conduitinlet 12, thereby maintaining the proper mixing action.

Referring to FIG. 6B, when micro-abrasive blasting device 75 is operatedin a vertical orientation, the spherical shape of mixing chamber 23 alsoassures a distal separation between the discharge conduit inlet 12 andthe particulate matter 50 at all mixing chamber 23 orientations.Additionally, the elimination of the delivery conduit internalsection—referred to in the embodiment of FIG. 3 as delivery conduitinternal section 34—assures that the pressurized gas stream enteringmixing chamber 23 at inlet port 27 always directs the pressurized-gasinto particulate matter 50 thereby eliminating the potential for backpressure on particulate matter 50.

Referring to FIG. 5, a discharge conduit stop 83 is attached todischarge conduit 10 so discharge conduit stop 83 moves with dischargeconduit 10 within mixing chamber 23 from inlet port 27 to discharge port29. Discharge conduit stop 83 provides a mechanical restriction to thedisplacement of discharge conduit 10 by creating a restriction at inletport 27 and discharge port 29. When discharge conduit stop 83 abutsinlet port 27, discharge conduit inlet 12 is properly positioned to sealmixing chamber 23. When discharge conduit stop 83 abuts discharge port29, discharge conduit inlet 12 is properly positioned to form separationgap 45. Discharge conduit stop 83 could be integral to discharge conduit10 through a flaring or bulging of discharge conduit 10, a componentmounted onto discharge conduit 10 via a gluing, swaging, heat-shrinking,or welding process etc., or simply a drop of dispensed glue.

Referring to FIG. 5A, as discharge conduit inlet 12 abuts inlet port 27,discharge conduit stop 83 is positioned at inlet port 27, restrictingdischarge conduit inlet 12 from protruding too deep through inlet port27. Preferably, discharge conduit stop 83 locates discharge conduitinlet 12 within inlet port 27 such that potential liquid residuesmoothly passes through micro-abrasive blasting device 75.

Referring to FIG. 5B, discharge conduit 10 is displaced so dischargeconduit inlet 12 no longer abuts inlet port 27. The displacement ofdischarge conduit 10 is restricted by the movement of discharge conduitstop 83 to discharge port 29. Preferably, discharge conduit stop 83locates discharge conduit inlet 12 at the geometrical center ofspherical mixing chamber 23.

Referring to FIG. 5C, the extension of delivery conduit 30 external tothe mixing chamber 23 facilitates a more narrow connection to the airabrasion device via a handheld pressurized-gas supply connector 55.Whereas, prior art devices connect to the mixing chamber body, thispreferred embodiment connects to a narrower delivery conduit 30.Therefore, the innovative micro-abrasive blasting device 75 may bemounted as a disposable tip onto a non-disposable handheld supplyconnector 55. While handheld supply connector 55 is held by the user'sfingertips, delivery conduit 30 of micro-abrasive blasting device 75mounts into handheld supply connector 55 downstream of the user'sfingertips. Because the innovative micro-abrasive blasting device 75does not support the user's grip and bulky supply connector,micro-abrasive blasting device 75 can be made shorter and of less rigidmaterial. This configuration greatly decreases the complexity and costof the micro-abrasive blasting device 75.

Additional Embodiments

Referring to FIG. 7, contiguous pipette structure 80 is extended toinclude an additional hollow bulb section to form a discharge conduitbearing 82. The discharge conduit bearing 82 is a tubular extension ofthe discharge port 29 section, elongated from a capped position end 95to a mixing position end 97 with a diameter equal to or greater thandischarge conduit 10. Discharge conduit bearing 82 provides mechanicalsupport to discharge conduit 10, to assure discharge conduit 10 properlydisplaces away from inlet port 27; a discharge conduit stop 83 isattached to discharge conduit 10 so discharge conduit stop 83 moves withdischarge conduit 10 within discharge conduit bearing 82 from the cappedposition end 95 to the mixing position end 97. Discharge conduit stop 83in conjunction with discharge conduit bearing 82 provides a mechanicalrestriction to the displacement of discharge conduit 10. When dischargeconduit stop 83 abuts capped position end 95, discharge conduit inlet 12is properly positioned to seal mixing chamber 23. When discharge conduitstop 83 abuts mixing position end 97, discharge conduit inlet 12 isproperly positioned to form separation gap 45.

Referring to FIG. 8, contiguous pipette structure 80 is extended toinclude a protective nozzle guard 85. Protective nozzle guard 85 isconstructed by extending pipette structure 80 so it encompassesdischarge conduit outlet 14, thereby providing protection to dischargeconduit 10 external to mixing chamber 23. Protection of the deliveryconduit is important to prevent damage to the delivery conduit duringshipping and from the delivery conduit puncturing other surroundingdevices in bulk packaging. Nozzle guard 85 also prevents the deliveryconduit from sticking the user when mounting micro-abrasive blastingdevice 75 onto the pressurized-gas connector.

Protective nozzle guard 85 may be removed prior to use, by pullingprotective nozzle guard 85 coaxially to discharge conduit 10, therebyfully exposing discharge conduit 10. Preferably, perforation to pipettestructure 80 is provided at nozzle guard separation point 87 as toweaken pipette structure 80 at nozzle guard separation point 87. Pullingon protective nozzle guard 85 coaxially to discharge conduit 10, causespipette structure 80 to separate at nozzle guard separation point 87allowing the removal of protective nozzle guard 85 to expose dischargeconduit 10.

Referring to FIG. 9, contiguous pipette structure 80 is extended toinclude a portion of a hollow bulb section to form a particle deflector90. Particle deflector 90 is constructed by extending pipette structure80 to preferably form a semi-spherical bulb structure. Particledeflector 90 is positioned on discharge conduit 10 as to deflectparticulate matter 50 ricocheting off the target surface during use.

Perforation to pipette structure 80 may be provided at particledeflector separation point 93 as to weaken pipette structure 80 atparticle deflector separation point 93. Pulling particle deflector 90coaxially to discharge conduit 10, separates particle deflector 90 atparticle deflector separation point 93 to permit the movement ofparticle deflector 90 along discharge conduit 10. Preferably particledeflector 90 is positioned near discharge conduit outlet 14 as todeflect particulate matter 50 ricocheting off the target surface duringuse.

Of course, pipette structure 80 may be constructed to include bothprotective nozzle guard 85 and particle deflector 90.

Mixing Method

Referring to FIG. 3C, a separation gap 45 between the delivery conduitoutlet 37 and discharge conduit inlet 12 generates rapidly expanding andcontracting gas-stream that forms a pressure gradient 48. The rapidexpansion of the gas-stream occurs as the gas-stream exits the narrowdelivery conduit outlet 37 and expands into the wider mixing chamber 23.The rapid contraction of the gas-stream occurs as the gas-stream flowsfrom the wider mixing chamber 23 into the narrower discharge conduitinlet 12. Because mixing chamber 23 is a closed-system, the volumetricflow rate into mixing chamber 23 must equal the volumetric flow rate outof mixing chamber 23.

Therefore, the expansion and contraction of the gas-stream acrossseparation gap 45 is accompanied by a localized pressure gradient 48 atseparation gap 45. Pressure gradient 48 across separation gap 45 withinmixing chamber 23 agitates particulate matter 50 causing particulatematter 50 to aerate. The aerated particulate matter 50 particles arepulled into the gas-stream at separation gap 45, generating an abrasiveladen gas stream into discharge conduit inlet 12 and out of dischargeconduit outlet 14. Because pressure gradient 48 across separation gap 45is independent of mixing chamber 23 orientations, agitation also isindependent of the orientation of mixing chamber 23.

This mixing method is independent of the mixing chamber shape as long asthe mixing chamber 23 is wider than the delivery conduit outlet 37 anddischarge conduit inlet 12. In the absence of delivery conduit outlet 37where delivery conduit 30 terminates at inlet port 27, this innovativemixing method still applies as pressure gradient 48 is formed acrossseparation gap 45.

Since separation gap 45 controls the rapidness by which the gas-streamexpands and contracts, the distance of separation gap 45 controls theagitation rate of particulate matter 50 within mixing chamber 23.Therefore, the quantity of particulate matter 50 introduced into thegas-steam is selectable by the position of discharge conduit inlet 12with respect to delivery conduit outlet 37 or inlet port 27.

Summary of claims from parent application Ser. No. 11/452,067 filed Jun.13, 2006

The following are representative of claims from the parent patentapplication.

A micro-abrasive blasting device may comprise:

-   -   a chamber having a chamber wall and a hallow interior;    -   a inlet port in said chamber wall;    -   a discharge port in the chamber wall;    -   a delivery conduit elongated from a delivery conduit inlet        external to said chamber to a delivery conduit outlet disposed        within the chamber and extending in fluid communications through        said inlet port;    -   a discharge conduit elongated from a discharge conduit inlet        internal to the chamber to a discharge conduit outlet external        to the chamber and extending in fluid communications through        said discharge port;    -   a quantity of particulate matter disposed within said chamber;        wherein a handheld pressurized-gas supply connector mounts to        said delivery conduit external to the chamber.

Pressurized-gas supplied to delivery conduit inlet may pass through thedelivery conduit outlet into the chamber to generate an abrasive ladengas stream out of said discharge conduit.

Said discharge conduit inlet may abut delivery conduit outlet to sealsaid particulate matter within said chamber.

Pressurized-gas supplied to delivery conduit inlet passes through thedelivery conduit and discharge conduit without entering the chamber.

Displacement of said discharge conduit inlet away from delivery conduitoutlet may unseal the chamber to allow pressurized-gas flow through thechamber to generate an abrasive laden gas stream.

The delivery conduit outlet may terminates at the inlet port of saidchamber.

The chamber may be spherical.

A discharge conduit stop may be mounted to said discharge conduit isdisposed within the mixing chamber to restrict the movement range of thedischarge conduit.

A pre-filled disposable pipette structure for micro-abrasive blastingdevice may comprise:

-   -   a hollow tubular pipette structure;    -   said pipette structure having a hollow bulb section forming a        mixing chamber;    -   said pipette structure further having a open ended hollow        tubular delivery section smaller in diameter and contiguous with        the bulb section, for delivery of pressurized-gas;    -   said pipette structure also having a hollow tubular discharge        section smaller in diameter and contiguous with the bulb        section, for discharging abrasive laden gas stream;    -   a quantity of particulate matter disposed within said mixing        chamber;    -   a discharge conduit elongated from a discharge conduit inlet to        a discharge conduit outlet;

wherein said discharge conduit is mounted in fluid communicationsthrough said discharge section of said pipette structure so saiddischarge conduit inlet is internal to the mixing chamber and dischargeconduit outlet is external to the mixing chamber.

A pressurized-gas connector may mount to said delivery section.

Pressurized-gas supplied to delivery section may pass through thedelivery conduit outlet into the chamber to generate an abrasive ladengas stream out of said discharge conduit.

The discharge conduit inlet may abut delivery section to seal saidparticulate matter within said mixing chamber.

Pressurized-gas delivered to delivery section may pass through thedelivery section and discharge conduit without entering the mixingchamber.

Displacement of said discharge conduit inlet away from delivery sectionmay unseal the mixing chamber to allow pressurized-gas flow through themixing chamber to generate an abrasive laden gas stream.

The pipette structure may be constructed of a thermoplastic materialselected from a group consisting of: polycarbonate, polyethylene,polyester, polystyrene, polypropylene, polysulfone, polyurethane, orethylene-vinyl-acetate.

The pipette structure may be formed by extrusion blow molding in atwo-piece mold.

The pipette structure may be formed by thermoforming a plastic tube.

The mixing chamber may be spherical.

The may be hollow tubular delivery section may be extended internal tosaid mixing chamber.

The pipette's hollow structure may be configured in cross section asselected from a group consisting of round, oval, square, rectangular andpolygonal shapes.

The pipette's bulb section may have a cylindrical configuration witheach end having a cone-shaped taper interfacing on one end with thedelivery tube section, and on the other end with the discharge tubularsection.

A method of using a handheld gas supply connector with a device forpropelling particulate matter may comprise the steps of:

-   -   placing particulate matter within a mixing chamber, said mixing        chamber comprising a mixing chamber wall, a inlet port at a one        end of the chamber and a discharge port at an opposite end of        the chamber and sized for completing at least one dental        procedure;    -   extending a gas delivery conduit disposed external to the mixing        chamber in fluid communications through said inlet port into the        mixing chamber to terminate at a delivery conduit outlet;    -   holding a pressurized-gas supply connector in a manner by        grasping said supply connector between two fingers of one hand        during the application of said device for at least one dental        procedure;    -   mounting said gas delivery conduit external to the chamber to        said handheld supply connector whereby the mixing chamber is        downstream of the fingers grasping location;    -   applying gas flow through the gas delivery conduit into the        mixing chamber;    -   discharging a mixture of gas flow and said particulate matter        through a discharge conduit in said discharge port for abrading        at least one target surface of a dental procedure.

The delivery conduit outlet may terminate at said inlet port of themixing chamber.

A method of sealing particulate matter within a device for propellingparticulate matter may comprise the steps of:

-   -   placing particulate matter within a mixing chamber, said mixing        chamber comprising a mixing chamber wall, a inlet port at a one        end of the chamber and a discharge port at an opposite end of        the chamber and sized for completing at least one dental        procedure;    -   extending a gas delivery conduit disposed external to the mixing        chamber in fluid communications through said inlet port into the        mixing chamber to terminate at a delivery conduit outlet;    -   inserting a discharge conduit in fluid communication through        said discharge port extending from a discharge conduit inlet        internal to said chamber to a discharge conduit outlet external        to the chamber;    -   positioning said discharge conduit inlet to abut said delivery        conduit outlet thereby sealing particulate matter within the        mixing chamber.

Pressurized-gas supplied to said gas delivery conduit may pass throughthe delivery conduit and discharge conduit without entering the mixingchamber.

Displacing said discharge conduit inlet away from said delivery conduitoutlet may unseal the chamber.

Delivering pressurized-gas to said gas delivery conduit may pass throughthe delivery conduit outlet into the chamber to generate an abrasiveladen gas stream out of said discharge conduit.

The delivery conduit outlet may terminate at said inlet port of themixing chamber.

A method for generating an abrasive laden gas stream within amicro-abrasive blasting device may comprise the steps of:

-   -   placing particulate matter within a mixing chamber, said mixing        chamber comprising a mixing chamber wall, a inlet port at a one        end of the chamber and a discharge port at an opposite end of        the chamber and sized for completing at least one dental        procedure;    -   extending a gas delivery conduit disposed external to the mixing        chamber in fluid communications through said inlet port into the        mixing chamber to terminate at a delivery conduit outlet;    -   inserting a discharge conduit in fluid communication through        said discharge port extending from a discharge conduit inlet        internal to said chamber to a discharge conduit outlet external        to the chamber;    -   positioning said discharge conduit inlet to have a separation        gap with said delivery conduit outlet;    -   applying a gas flow through the gas delivery conduit into the        mixing chamber whereby forming a pressure gradient across said        separation gap;    -   aerating said particulate matter to mix with the said gas flow;    -   discharging a mixture of gas flow and said particulate matter        through a discharge conduit in said discharge port for abrading        at least one target surface of a dental procedure.

The delivery conduit outlet may terminate at said inlet port of themixing chamber.

In addition to the above, the following are disclosed but may not havebeen claimed in the parent application:

A micro-abrasive blasting device may comprise:

a chamber having a chamber wall and a hollow interior;

an inlet port in said chamber wall;

a discharge port in the chamber wall;

a tubular delivery conduit section contiguous with said chamber wallelongated from a delivery conduit inlet external to said chamber to adelivery conduit outlet terminating at said inlet port;

a tubular discharge section contiguous with said chamber wall elongatesfrom said discharge port external to said chamber;

a discharge conduit elongated from a discharge conduit inlet internal tothe chamber to a discharge conduit outlet external to the chamber andextending through said tubular discharge section and in fluidcommunications with said tubular discharge section;

a quantity of particulate matter disposed within said chamber;

wherein a handheld pressurized-gas supply connector mounts to saidtubular delivery conduit section external to the chamber;

wherein:

a discharge conduit stop mounted to said discharge conduit is disposedexternal to the mixing chamber to prevent the extraction of thedischarge conduit out of the tubular delivery conduit section andtubular discharge section.

A discharge conduit bearing may comprise a elongated tubular extensionof the discharge port extending from the mixing chamber, a portion ofwhich has a diameter equal to or greater than the discharge conduit;

wherein the discharge conduit stop is disposed within the dischargeconduit bearing.

A micro-abrasive blasting device may comprise:

a mixing chamber comprising a wall, an inlet port disposed in the walland a discharge port disposed in the wall;

a delivery conduit extending from external the mixing chamber to theinlet port;

a discharge conduit extending from internal the mixing chamber, throughthe discharge port, to external the mixing chamber, and having adischarge conduit inlet disposed within the mixing chamber; and

a discharge conduit bearing comprising a elongated tubular extension ofthe discharge port extending from the mixing chamber, a portion of whichhas a diameter equal to or greater than the discharge conduit;

wherein the discharge conduit stop is disposed within the dischargeconduit bearing.

A micro-abrasive blasting device may comprise:

a mixing chamber comprising a wall, an inlet port disposed in the walland a discharge port disposed in the wall;

a delivery conduit extending from external the mixing chamber throughthe inlet port to within the mixing chamber; and

a discharge conduit extending from internal the mixing chamber, throughthe discharge port, to external the mixing chamber, and having adischarge conduit inlet disposed within the mixing chamber.

The delivery conduit may extend to within the mixing chamber.

A micro-abrasive blasting device may comprise:

a mixing chamber comprising a wall, an inlet port disposed in the walland a discharge port disposed in the wall;

a delivery conduit extending from external the mixing chamber to theinlet port;

a discharge conduit extending from internal the mixing chamber, throughthe discharge port, to external the mixing chamber, having a dischargeconduit inlet disposed within the mixing chamber, and having a portionincluding a discharge conduit outlet disposed external the mixingchamber; and

a protective nozzle guard extending from the mixing chamber andencompassing the discharge conduit outlet

A particle deflector may be positioned on the discharge conduit, in theform of a semi-spherical bulb structure, for deflecting particulatematter ricocheting off a target surface during use.

A micro-abrasive blasting device may comprise:

a mixing chamber comprising a wall, an inlet port disposed in the walland a discharge port disposed in the wall;

a delivery conduit extending from external the mixing chamber to theinlet port;

a discharge conduit extending from internal the mixing chamber, throughthe discharge port, to external the mixing chamber, and having adischarge conduit inlet disposed within the mixing chamber; and

a particle deflector positioned on the discharge conduit, in the form ofa semi-spherical bulb structure, for deflecting particulate matterricocheting off a target surface during use.

Summary of claims from parent application Ser. No. 12/551,416 filed Aug.31, 2009

The following are representative of claims from the parent patentapplication.

A micro-abrasive blasting device comprising:

a mixing chamber comprising a wall, an inlet port disposed in the walland a discharge port disposed in the wall;

a delivery conduit extending from external the mixing chamber at leastto the inlet port; and

a discharge conduit extending from internal the mixing chamber, throughthe discharge port, to external the mixing chamber, and having adischarge conduit inlet disposed within the mixing chamber;

wherein the discharge conduit is movable and,

in a first position, the discharge conduit inlet abuts the inlet port toseal particulate matter in the chamber until use; and

in a second position the discharge conduit inlet is displaced from theinlet port.

The discharge conduit may be disposed opposed the gas delivery conduit.

In the second position, pressurized gas supplied to the delivery conduitflows through the delivery conduit into the mixing chamber, andparticulate matter in the chamber mixes with the flowing gas and isdispensed through the discharge conduit. A separation gap between thedischarge conduit inlet and the inlet port controls an agitation rate ofparticulate matter within mixing chamber, and therefore a quantity ofparticulate matter introduced into the gas steam is selectable by thedisplaced position of discharge conduit inlet with respect to the inletport.

The discharge conduit may be in the form of a nozzle. A nozzle guard mayprovide protection to the discharge conduit.

Abrasive powder may be disposed in the mixing chamber; the mixingchamber may be spherical so as to assure a distal separation between thedischarge conduit inlet and the abrasive powder at all mixing chamberorientations. The discharge conduit inlet may be centered within thespherical mixing chamber.

The device may comprise a thermoplastic material selected from a groupconsisting of: polycarbonate, polyethylene, polyester, polystyrene,polypropylene, polysulfone, polyurethane, or ethylene-vinyl-acetate.

Advantages

From the description above, the following advantages may become evident:

(a) Use of the delivery conduit to seal the mixing chamber, thereby:

1. reducing the component count; and

2. making disposable pipette structure usable for air abrasionapplications.

(b) Use the delivery conduit to create a bypass to the mixing chamber,thereby eliminating liquid entrapment within the mixing chamber.

(c) Extending the delivery conduit external to the mixing chamber,thereby making the device adaptable to a handheld gas supply connectorand standard tube fitting.

(d) Generation of a localized pressure gradient within the mixingchamber to generate and control powder agitation rates.

(e) Use of a spherical mixing chamber to deliver consistent powderperturbation at all mixing chamber orientations.

(f) Simplified construction using contiguous pipette structurefabricated to form the body of the micro-abrasion device.

While the invention has been described, disclosed, illustrated and shownin various terms or certain embodiments or modifications which it hasassumed in practice, the scope of the invention is not intended to be,nor should it be deemed to be, limited thereby and such othermodifications or embodiments as may be suggested by the teachings hereinare particularly reserved especially as they fall within the breadth andscope of the claims here appended.

SUMMARY, RAMIFICATION, AND SCOPE

The present invention may accomplish the above-stated objectives, aswell as others, as may be determined by a fair reading andinterpretation of the entire specification.

Accordingly, the reader will see that the micro-abrasive blasting devicemay have reduced components, simplified construction, enhanced mixingmethodology, and mountable to handheld gas supply connector.

Furthermore, the micro-abrasive blasting device has the additionaladvantages in that

-   -   it provides a more narrow pressurized-gas supply connection.    -   it provides a sealed device that is resistant to fluid        contamination.    -   it provides a reliable device that delivers a consistent        quantity of abrasive at any orientation.    -   it provides the user with ability to select powder delivery        rates by external manipulation of the discharge conduit        position.    -   it provides a simplified construction methodology which reduces        the manufacturing cost of the product.

Thus the scope of the invention should be determined by the appendedclaims and their legal equivalents, rather than by the examples given.

1. A method of performing a dental procedure, comprising: providing amicro-abrasive blasting device comprising: a mixing chamber; a gasdelivery conduit extending from the mixing chamber; and a dischargeconduit extending from the mixing chamber; providing a handheldpressurized-gas supply connector; mounting the micro-abrasive blastingdevice by its gas delivery conduit into the handheld supply connector;in use, when the micro-abrasive blasting device is held by a user'sfingertips, the mixing chamber is oriented downstream of the user'sfingertips.
 2. The method of claim 1, wherein: the gas delivery conduitmounts into the supply connector downstream of the user's fingertips. 3.The method of claim 1, further comprising: providing particulate matterwithin the mixing chamber; supplying pressurized-gas, via the supplyconnector, to the gas delivery conduit; and generating an abrasive-ladengas stream out of said discharge conduit.
 4. The method of claim 1,further comprising: applying a gas flow through the gas delivery conduitinto the mixing chamber; aerating said particulate matter to mix withthe said gas flow; discharging a mixture of gas flow and saidparticulate matter through a discharge conduit in said discharge portfor abrading at least one target surface of a dental procedure.
 5. Amethod of making a micro-abrasive blasting device pipette componentcomprising a mixing chamber having a wall, an inlet port disposed in thewall, and a discharge port disposed in the wall, the method comprising:forming a gas delivery conduit extending from external the mixingchamber to the inlet port, and having an inlet end; forming a dischargeconduit extending from the discharge port, to external the mixingchamber, and having an outlet end; sealing one of the inlet anddischarge ends during a blow-molding process to entrap pressurized-gasfor forming the component during a blow-molding process.
 6. The methodof claim 5, wherein the gas delivery conduit is narrower than the mixingchamber.
 7. The method of claim 5, wherein the sealed end is the inletend, and further comprising: puncturing or cutting the sealed end topermit air flow into micro-abrasive blasting device.
 8. The method ofclaim 7, wherein puncturing or cutting the sealed end is effected bymounting the device to a pressurized gas connector.
 9. The method ofclaim 5, wherein: the pipette component is formed by extrusion blowmolding in a two-piece mold.
 10. The method of claim 5, wherein: thepipette component is formed by thermoforming a plastic tube.
 11. Themethod of claim 5, wherein: the mixing chamber comprises bulb sectionhaving a cylindrical configuration with two ends, each end having acone-shaped taper; and interfacing on one end with the gas deliveryconduit, and on the other end with the discharge conduit.
 12. The methodof claim 5, further comprising: constructing the air abrasion device outof a continuous tubing.
 13. The method of claim 5, wherein: the devicecomprises a thermoplastic material selected from a group consisting of:polycarbonate, polyethylene, polyester, polystyrene, polypropylene,polysulfone, polyurethane, or ethylene-vinyl-acetate.
 14. A method ofselectively sealing particulate matter within a device for mixing andpropelling particulate matter, the method comprising the steps:providing a mixing chamber comprising a wall, an inlet port disposed inthe wall and a discharge port disposed in the wall; providing a gasdelivery conduit extending from external the mixing chamber to at leastthe inlet port, and having a delivery conduit outlet; providing adischarge conduit extending from internal the mixing chamber, throughthe discharge port, to external the mixing chamber, and having adischarge conduit inlet disposed within the mixing chamber; andpositioning the discharge conduit inlet to abut the delivery conduitoutlet for selectively sealing particulate matter within the mixingchamber.
 15. The method, according to claim 14, wherein: with thedischarge conduit inlet abutting the delivery conduit outlet,pressurized gas supplied to the gas delivery conduit passes through thegas delivery conduit and the discharge conduit without entering themixing chamber.
 16. The method, according to claim 14, furthercomprising: displacing the discharge conduit inlet away from thedelivery conduit outlet; wherein with the discharge conduit inletdisplaced away from the delivery conduit outlet, pressurized gassupplied to the gas delivery conduit passes through the gas deliveryconduit and enters the mixing chamber.
 17. The method, according toclaim 16, further comprising: providing particulate matter within themixing chamber; supplying pressurized-gas to the gas delivery conduit;and generating an abrasive-laden gas stream out of said dischargeconduit.
 18. The method according to claim 14, wherein: said deliveryconduit outlet terminates at the inlet port of the mixing chamber. 19.The method according to claim 14, wherein: the gas delivery conduitextends through the inlet port into the mixing chamber; and the deliveryconduit outlet terminates at the inlet port of the mixing chamber. 20.The method of claim 14, further comprising: providing means forpreventing extraction of the discharge conduit from the discharge port.